DESCRIPTION: Over the past decades, antidepressants and psychotherapy have been the first-line treatments for LLD. Despite being safe and well-tolerated, a large number of patients do not achieve full and persistent remission after initial treatment. About 50% of patients with LLD do not respond after two antidepressant trials, meeting the consensus definition of treatment resistance (TR-LLD). The persistence of chronic and elevated depressive symptoms in older adults has significant clinical and public health implications. This has been correlated to poor general health, reduced quality of life, and a higher risk of mortality when compared to those with sustained remission after treatment. Despite the